Method of rontgenological reproduction



April 18, 1933. H. F. KURTZ 1,904,867

METHOD OF RbNTGENOLOGICAL REPRODUCTION Filed Sept. 26, 1927 2 Sheets-Sheet 1 HENRY F. KU RTZ lNVENTOR 15 ATTONES April 18, 1933. H. F. KURTz 1,904,867

METHOD OF RNTGENOLOGICAL REPRODUCTION Filed Sept. 26, 1927 2 Sheets-Sheet 2 Y O H F G H l2 l Y K INVENTOR Fla-4 HENRY F. KURTZ.

LSATTORN s Patented Apr. 18, 1933 3m F; KURTZ, 0F noonnsm'nn; NEW YORK,

AssIGivoR To BAnscii 85 mm; enrich;

5 METHOD or BUNTGENOLOGQIACAL imrno'nucmonwf i Applicationfiled September 26 1921.; se i No/222L131!" II This i elatesto Rontgen ology and more p articnlarlyvit is concerned with meth ods and apparatus iwhereby i Rontgenograins may beprodnced and viewed stereoscopic l y-m M t. in

Qne of the most important objectsof the present invention iis to provide "methods and i means for Rontgenological reproduction in which oX-iraystereograrns' are produced I and ewed t at t e, e 'qi mt d cbm ort ablestereoscop ie views are afforded.

V Other; objects are to produce X-ray stieol grams which are-to be viewed nnder certain .conditions;, to: view Xi-ray" stereograrns which have been produced under certain con ditions and to. provide" eificient means for e'f-' fectingthe production. and viewingoi": X 'ray stereograms according to my invention.

i'lheusual practice in stereographie Bent tion of a foreign body or a pathological con dit on,.for example. 8111106311 operatmg sur Q8011 is Very often gnidedsolely the findings ofvan X rav examination; itis evident that thef valne of true and accurate stereoseopicviews cannot beoverestimated.

The d fficulties and inaccuracies of: the prevailing methods ofi .X-ray stereoscopy are eliminated by employing ny improved methods-and apparatus: As will hereinafter be more fully explained, 'accui atean'd conifort able stereoscopic v sion 1s dependent upon the roper observance and correlation ofcerprinciples ,ofvi's'i'on, n

, e er v 1 the Figi-l is a diagr minatic View illnstrating my method of-exposurekiT, V

E'Fig. 2 is ajdiagrammatic, view -lshowing an incorrect viewing method in Which icbnvergence and accommodation are not Fharlnon ized fl I I Fig.3 is my improved method viewing stereograms.

(Fig? 451 a dij graf hma ticfiview which shows 1w areflecting stereoscope adapted for "viewing lai' eiste e glm e l d d i i t0 my'present IIIYGIltlOIlL v 1 i The general condltlonsnecessary for accu} rate V and comfortable {stereoscopic vision 1 are aharmony 'etween accommodation and cona diagrammatic vie'vv illustratingvergenc'e andfa precise, definite difi'erence in Acco m da is the the foeus Of the eye tobring divergentrays accommodation necessarilyvaries for objects loeated at different distance s.; Convergence is the ability to directthe visual lines of the two eyes to a near pointQj I f jQn looks "at a power of varying perspective betwe en the vievvsmpresented to retina and' the amount of distant objectaccommodationis relaxed and thelines of sightjare parallel, but forviewing a near objeetit is necessary ,to accommodate and alsoto converge for the" panticnlai dis: tance. When convergence is effected for one distance and a oconnnodationis' Aefiected forfa nt distance simnltaneolisly, the result-i di r ingi recompositlon is naccurate and very i comfortable. Th s result is invariably pr c e/h n the uslial methodsfbf reosop1 R iteen s're j ihp yed A cqmni datlOIl and convergence are correspondingly associated andfor a given distancethei els V one degreeof accommodation and a corresponding singhdegreeof convergence. 3 q I When 'anobject is viewed at a definite distance with both eyes, the view presented to the left eyedifiers in iperspelctivefrorn that presentedtothe right eye. It is'jalso trl'ie ent distances are different in perspective. In

, that views of the same objectseenffrom differ o r wo ds, the "right i and left views will difler if rorn feach other at any distance an a pair oif views'willvlary vv iththedistanee. q

- varies from '27 to 36 inches.

The fulfillment of the conditions of harmony between accommodation and convergenes and a difference in perspective between the views which is correct in aspect, but of any degree, is sufficient for the production of relief effects or plastique. However, in order that the degree of plastique shall not be excessive or insufficient, that is, that the third dimension; shall be precise, the fulfillment of a third conditionis necessary. Thiscondition is dependent upon the fact that the degree of difference in'perspectivebetween the right and left views increases as the viewing distance decreases. The difference-at a'given distance therefore specific to that distance. This, interpreted in terms of Rontgenological stereoscopy means that negatives or stereograms taken at a given distance must be viewed at the same distance, or under geometrically homologous conditions which can be secured by a properly designed viewing device. v e

' In order to more clearly explain and describe my invention, X-ray stereograms of the human chest will be used by way of illustration. It is obvious, however, that my invention is not limited to Xray stereograms of the human chest, as it may be applied with equal effect and advantage to the Rontgenological examinations of any object or objects. In the usual practice of making X-ray stereograms of the human chest, the exposure distance, that is, the distance from'the plane of thefocal point or anode of the X-ray tube to the sensitized element, is usually anywhere from 20 to inches. tereograms exposed at this distance are then usuallyviewed in a device having a viewing distance which Such practices violate the aforementioned principles of accurate stereoscopic vision and one viewing such stereograms of the chest experiences discomfort, besides receiving an impression generally thatthe chest lacks depth to a marked The first requisite in the development of my improved method is theestab-lishmentof a normal viewing distance. This may be de- 6 fined asthat distance between the eyes and an object that results in maximum plasticity consistent with comfort. The nearer, within reasonable limits, an object is to the eyes the more pronounced is the plasticity, that is, the impression of relief or third dimension becomes more pronounced as the distance diminishes. Experience shows that an object may be comfortably viewed at a distance of 15 inches, but that as the distance becomes less, vision'becomes diflicult because of the severe accommodative effort. The average person with. active accommodation sees comfortablyat '10 inches, but allowing for variation in individuals, it is reasonable toassume 15 inches asa normal viewing distance. Although I have used 15 inches as the normal viewing distance in this specification, it is for illustration only, and it is to be distinctly understood that I do not limit my invention to a normal viewing distance of 15 inches.

WVhen a normal viewing distance has been established, the convergence angle is automatically established, sinceit must be the angle subtended by average interpupillary distance, namely, 2 inches, at normal viewing distance. Since 15 inches has been selected as normal viewing distance for purposes of illustration in this. specification, the convergence angle of my illustration will be the subtense of 2 inches at a distance of 15 inches. The interpupillary distance of 2 inches is an average and is by Way of illustratio n only, as my invention is not limited to an interpupillary distance of 2 inches.

In order to produce X-ray stereograms in accordance with my method, this would mean that the X-ray tube would be positioned only 15 inches from the sensitized element and-that the tube would be shifted only 2 inches between successive exposures. As it is obviously impossible to work at this distance, other expedients must be resorted to'in order to obtain correct convergence conditions in accordance with my invention.

Upon experiment, it was found that a dis tance of 45 inches from the anode of the X-ray tube to the sensitized element is suitable. At this distance the entire chest of the larger subjects is projected upon a 14" x 17 film when exposed with the necessary tube shift. In order to meet the convergence conditions required by my invention, it is necessary to shift the X-ray tube 7 inches between successive exposures when working at anexposure distance of 45 inches. The triangle represented by the subtense of 7 inches at 45 inches is mathematically proportional to the triangle represented by the subtense' of 2 inches at 15 inches. Although I have used 45 inches as an exposure distance, and 7 inches as a tube shift, it is by way of illustration only, and it is to be understood that my invention can be equally well applied to other exposure distances and tube shifts.

Fig. 1 of the drawings illustrates my method of producing X-ray stereograms by successively exposing two sensitized elements to a source of Xrays, the X-ray tube being shifted between exposures. The anode of the X-ray tube, indicated at 10, is located at the full-line position for the exposure of the first negatives and is laterally shifted to the dotted line position for exposure of the second negative. The tube shift or separation between exposures of the two sensitized elements is indicated at AB, the tube shift for the illustration under consideration being equal to 7 inches. The distance from the plane of the X-ray tube anode to the sensitized element. which is called the exposure distance, is indicated at CD and for the example chosen this converge for 15 in he swims distance is equaltol5 inches. The two sposi- 'itlOIlS iofathe Xe-ray source andthe, eometrical nenter of thezsensitizedelement de eqazplane which is to the sensitized eleimaginarymxialflinejoG iliesin this plane.= The sensitized elementsh, which may be either platens film, are indicated at positions occupied during? exposure, and if the right eye could be placed in thelposition occupied 'bythe Xmay source :fior theex posune of the first film l1 and if the leliteye could be placed at the position occupiedlay the :sounce for :the exposure of the second film 1 2,21 precise 'comzfiortable View would he received promidi-11g the right eye could View only the negatime 11 and the left @eye only negative 12, This, however, is impossible because an interpupillary distance of 7% inches does not exist and because such an :arnangement would not permit selectivitytor'each indiyidualaeye.

Figure 2 illustrates :a viewing arrangement which is designed to-oyencome these two unficulties. In "this arrangement film ll, which was exposed when the X-nay sou-roe lOwvas located the full line position at the rightin Fig. 1, is offset to the left of the axis line 0Q "a distance -FG which this illustration is equal to 2 inches. The vfilm :12, which was exposed when the source 1 9 was'locaited rat" the dotted line position shown in Fig. 1-,:is offset to the right a distance which is equal to 2% inches the'fillustration p under considenation. a a 1 i This arrangement allow-s yision, nnder the correct convergence with interpupillary distance of 21/ incheshetween theeyes E, E. It is to be understood thatthese ofisetti-ng movements inyolvetranslation only, with no rotation and vit to be further understood that the films '11 and 1-2are Very small so that the offsetting movements will completely se p- "arate the fi hns. vThe amount of oflset of the films in any case is obtained by subtracting the interpupill-ary distance itromthe X-ray tube shiftand dividing the remjainderhy two. It will be observed that the visual {axes of the :two eyes E, ,E intersect ata point whose :distancefrom the eyes is denoted by In the illustration under consideration this distance 1K is equal :to' 15 inches,- which was assumed as the normal iewing. )distame; .Although this arrangementlulfills theiconwergence requimement, it d-oes not-gerovide precise, comfortable" :stereoscopy -'s1nce accommodation and convergence do notharmoni'ze, as'the eyeslare attempt-'mg to BJCCGIfi modate for 45 inches 'zand at the same time to Elfin ordertoiipuovid'e for fiharmony a oomxnodation and,;conv engzence,, l ipositicn a negative. lens :14,; before each eye' E, E ms clearly shown: in i3. These less e o ichosemthat; they, will image thefilms 3L1 and .lfiza'tca :plane which is located at normal y-icwingndist-ancexfrom the eyes, in :this'. inches. Hence, the convergencegand .modation'lare harmonized :asitheeyes nrehoth accommodating and convergingifor a distance of 15 inches. 1 The lenses .154, I15

comparatively weak, say. about 2 dioptres, and sums they'areplaced close thenodal lot the eyes, the :angles subtended by the images .fio-rmed by these lenses .5;

equal, within the limits of negligible; amount, to :those subtended by the :films when viewed without lenses. The arrangement oztFig fi,

thenefore, illustrates a correct method of Viewing, ing to my invention, {stereo-4 gramswhichi-are small enongh to be11;entire-' ly separated ill-before explained. I ,As will v ofiaendoethe;

size, sayyldgx lv'i inches for example softhat the oflset il-lustrated in Fig.

case, the stereograms will beef a companeti'uely lailfgfi I by theoflset introducedaas heme ,pletely separate thefilmsg V Since it is }essential that each eye sees its respective stereognam, recourse must be had to-the reflecting type of; r s opewhi n viewing comna-mtively large size filnis osnsteneogirams y :The ause of azreflecting, type of stereosco pe' for viewing large.,=fihns,,.;in accordance with -myin entionQis illustrated in .F .4 ,of the drawings. The relati elylwrge @ray l'fi-hans or stereognams-are-indicamd at 11 and 12, film 1 1'? :being produced with the X,-ma y source in; if ullfline position of F and film J12, t being-ppnoduoed with the source in dotted line :positionatthe left inFig. L As olearly illustratzed, the films l1, and 1-12, are; positioned latenailly :respect the wieyving device. improved viewingdevieea comprises two angularly disposed ,meflectors M, which su f" are adapted *toneflect the images ofthetwo 1 v films or stereograms 11',.;l2'.. Cooperating I i these a m-irrors are, the negativefllenses M',1 5' whereby,the reflected images gane imaged ata plane PL which ,is located at normal viewing distance in :front of the eyes E of the observer. I The reflectors M, :M

are-positioned; so that each lies {at an angle of substantially-4 5degneesto-theaxisgQOf, each refieetor A el-11g perpendicularzto vplane which is defined by the-two positions of theX-ray 'sourcelandthecenteroff the zfilm, as shown 1 in Fig. 2, and so that this: ,plane pie/noes thej reflectoars afimidmeight, y

The'axis O0" is imaged normally F130, itself and extends to the right and left as shown at BBC The films-111,112 aresojpositioned I that their centers are ofiset from theimaged axis RR? a; distance "1 The amountof the offset Sfl 1's ea-lcu latedin the same; manner as the offset FG in Fig. 2, namely, by subtracting the interpupillary distance from the tube separation and dividing the remainder by two. The optical paths from the eyes to the mirrors and thence to the films are shown 'vention,-it is essential that the optical path from-the eye to the reflector and thence to the film should be equal to the exposure distance. As indicated on Fig. 4, the distance X plus the distance Y equals the exposure distance GD. Although I have shown two plane reflectors M and M, it is obvious that other reflecting means, such as prisms, may also be used. If prisms are used for reflectors, the

glass path ofg'the prisms must be reduced to air path in determining the distances at which'the filmsare located. I

WVith the arrangement illustrated in Fig. 4, precise andcomfortable stereoscopic views may be obtained in accordance with my invention, as the eyes E, E are both accommodating and converging for the image-plane PL which is positioncd'at normal viewing distance in frontof the eyes of the observer. The convergence angle," which is the angle formed bythe intersecting visual axes of the two eyes,' is-indicated at W.

In order to obtain precise and comfortable stereoscopic views, it is essential that the various distances and locations, hereinbefore described, be strictly observed. In other words,

a pair of films taken under the assumed specifi'c conditions as to convergence and expo sure distance, must be located 111 the stereoscop'e' 1n only one position w1th respect to the optical axes of the stereoscope and'of the exposure apparatus in order that they may be viewed under these specific convergence conditions. I This precise location of films can be effected by using suitably arranged indicia means. Such means may take the form of a pair of points made of material which is opaque to X-rays and located on the film holder or casette, whereby a trace of these marks will be made on the exposed films. A

pair of properly arranged marks are, ar-

ranged on' the film holders of the viewing device so that the films will be properly located when the marks on the films are placed in register with the marks on the; viewing device.

'It is to be understood that the'films or stereograms to be viewed are placed in front of the usual illuminated'viewing boxes as are well known to one skilled in the art. jMyinventiOn is not limited to the use of a normal viewing distance of '15 inches and an exposure distance of 45 inches, asth-ese specific figures are by way of illustration only and it is obvious that my invention can be exposing distances.

to normal viewing distance:

to other viewingand It is also obvious that various modifications can be made without departing from the spirit of my invention and the" specifications and accompanying drawings are to be interpreted as illustrative only and not in any limiting sense.

From the foregoingit will be apparent that I am able to attain theobjects of my invention and provide methods and means for effecting Rontgenological reproduction which is characterized by precise, accurate stereoscopic views. 1

I claim; v

1. A method tion which comprises producing X-ray stereograms by successively exposing two sensiequally Well applied tized elements to a source of X-rays located at a predetermined distance fromsaid elements, shifting said source a certain distance between successive exposures, developing said exposed elements to produce X-ray stereograms, forming images of said stereograms at the exposure distance, forming images of said first named images at normal viewing distance from an observers' eyes and viewing said'images under a convergence angle that is substantially the-same as the angle subtended by the shiftof said source at the predetermined exposure distance.

2. A method of producing X-ray stereograins which comprises establishing an ex posture distance which'is greater than normal viewing distance, successively exposing a pair of sensitizedelements to a source of X-rays, shifting the source of X-rays between the successive exposures, and developing the exposedelements, the relation of the amount of shift of'said source to the exposure distance being substantially the same as the relation of average interpupillary distance 3. A method of producing grams which are to be viewed at a predetermineddistance and angle of convergence,

which comprises locating a sensitized element at a predetermined exposure distance which is greater than normalvi'ewing distance from a source of X -rays', exposing said element to X-rays from said source, shlftlngsaid source a predetermlned distance, replacing said eleof Rontgenological reproduc- X-ray stereo- I ment with a second sensitized element, ex- I posing said second element, and developing both of said elements, the angle subtended by said distance of shift at said exposure distance being substantially the same as the angle subtended" by average interpupillary distance at normal viewing distance.

1-. The step in a method. of producing a pair of X-ray stereograms which comprises establishing a predetermined exposure distance from the plane of an X-ray source to the plane of a' sensitized element. WhlOh'IiS greater than normal viewing distance and a predetermined shift of said source, the ratio ing distance.

.source at the exposure distance viewing distance, successively exposing a, t

of said shift to said exposure distance being substantially the same as the ratio of average interpupillary distance to normal view- 5. A method of zexamining X-ray stereograms which have been produced by successively exposing sensitized elements to a source of X-rays located at a predetermined distance WhlCh is greater than normal vlewing distance, and shifting said source a certa1n distance between successive exposures,

which comprises forming images of said stereograms at normal vlewlng dlstan'ce and viewing said images'under a convergence angle which is substantially the same as the angle subtended by the distance of shift of said ments. y I

6. A method of stereoscopicallyirecomposing a pair of X-ray stereograms Which have been produced by successively exposing two sensitized elements to a source of X-rays at a predetermined distance which is greater than normal viewing distance and shifting the source a predetermined distance between successive exposures, which comprises positioning said stereograms at a distance from the eyes of the observer which is substantiallythe same as the exposure distance of said stereograms, each stereogram beingoffset a predetermined distance from the median plane passing between the eyes of the observer, forming images of said stereograms at substantially normal viewing distance, and viewing said images. i

7. A method of stereoscopically recomposing a pairof X-ray stereograms, which have been produced by successively exposing two sensitized elements to a source of X rays at a predetermined distancewhich is greater than normal viewing distance and-shifting the source a predeterminedv distance between successive exposures, which comprises locating said stereograms at a distance from the observers eyes which is substantially the same as the exposure distance of said stereograms, formingimages of said stereograms at normal viewing distance and viewing one image with oneeyeand the other image with 1 the other eye. a

8. A method of producing X-ray stereograms which comprises establishing anexposure distance which is greater than normal pair of sensitized elementsto a source of X- rays, shifting the source of X-rays between the successive exposures, anddeveloping'the exposed elements, the relation of the amount a of shift of said source to the exposure distance being substantially the same as the relation of the average interpupillary distance to nor mal viewing distance.

HENRY F. KURTZ,

of said ele- 

